Although the amino acid composition of fishes and some marine invertebrates varies among taxa and systems, similar information is lacking for freshwater invertebrates. The objectives were to characterise and compare the amino acid composition among different aquatic species, dietary habits, and environmental conditions. Benthic macroinvertebrates from different functional feeding groups (FFG), bulk zooplankton, biofilm, and fishes representing 12 families (21 genera or species) were collected from temperate lakes in eastern Canada during the summers of 2013 and 2014. Fifteen protein‐bound amino acids, including thiols, were measured in whole invertebrates, biofilm, or fish muscle. We hypothesised that the amino acid composition will differ among species and systems. Multiple discriminant analyses revealed significant differences in the amino acid composition among species—based on varying percentages of cysteine (as cysteic acid) and histidine—and among FFG/trophic designations—based on histidine and lysine—where the primary consumers were more variable than the predators. Overall, the results suggest that patterns were based on phylogenetics, biological characteristics, and the FFG/trophic designations of biota. The within‐taxon variability in composition was also related to differences among lakes. Characteristics of their environment, including lake pH and the food web structure (abundance and composition of taxa), probably influenced their dietary habits and amino acid composition of diet. These results expand the currently limited knowledge of the biochemical composition of freshwater biota and provide impetus for further studies on nutritional values in predator‐prey relationships, trophic guilds, and the biomagnification of protein‐bound contaminants through food webs.

中文翻译：

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淡水食物网中的氨基酸：评估它们在分类群、营养水平和系统之间的变异性

尽管鱼类和一些海洋无脊椎动物的氨基酸组成因分类群和系统而异，但淡水无脊椎动物缺乏类似的信息。目的是表征和比较不同水生物种、饮食习惯和环境条件之间的氨基酸组成。2013 年和 2014 年夏季，从加拿大东部的温带湖泊中收集了来自不同功能摄食群 (FFG)、散装浮游动物、生物膜和鱼类的底栖大型无脊椎动物，代表 12 科（21 属或种）。 15 种蛋白质结合氨基酸，包括硫醇在内，在整个无脊椎动物、生物膜或鱼肌肉中进行了测量。我们假设氨基酸组成会因物种和系统而异。多重判别分析揭示了物种间氨基酸组成的显着差异——基于半胱氨​​酸（作为半胱氨酸）和组氨酸的不同百分比——以及基于组氨酸和赖氨酸的 FFG/营养名称之间——其中主要消费者比掠食者。总体而言，结果表明模式基于系统发育、生物学特征和生物群的 FFG/营养名称。组成的内部分类变异也与湖泊之间的差异有关。它们的环境特征，包括湖泊 pH 值和食物网结构（分类群的丰度和组成），可能影响了它们的饮食习惯和饮食中的氨基酸组成。